In order to make it possible to efficiently utilize hydrogen as an energy carrier, suitable storage of the gas is important. This requires cost-effective, lightweight vessels which are suitable for mass production and which on the one hand withstand particularly high pressures and pressure fluctuations as well as (low) temperatures and temperature fluctuations and on the other hand are protected from the reactivity of the hydrogen gas. In addition, the pressure vessels, also referred to as pressurized gas vessels, have to reliably withstand external mechanical loading.
In order to make it possible to efficiently utilize hydrogen as an energy source, it is necessary for large quantities of the gas to be stored in a small space. Minimization of the space required for storing the gas simultaneously correlates to an increase in the internal pressure. The increase in the internal pressure and associated large pressure fluctuations increase the demands made in respect of the mechanical stability of the pressure vessels considerably.
Mechanical damage to the pressure vessels from the outside is very dangerous and therefore has to be avoided without fail. The demands made on the pressure vessels also increase with a view to this aspect, in particular with the increase in the internal pressure. Moreover, it should be possible to dispense with complex containments, as would be necessary for preventing damage caused, for example, by accidents (vehicle collisions) or bombardment.
The microstructure of uncoated steel materials can be negatively affected/altered by the penetration of hydrogen into the material. In this respect, reference is made in particular to what is termed hydrogen embrittlement. Through alternating changes in load, for example large fluctuations of the internal pressure in a hydrogen gas tank, this can lead to an increased extent to material failure. Protection by a conventional surface coating, for instance a lacquer coating or a metallic covering through, for example, zinc plating, cannot permanently prevent hydrogen from attacking the microstructure of carbon steel or low-alloyed steel.
It is known from the prior art to produce vessels for storing hydrogen from a plurality of layers, to be precise from an inner layer made of a high-grade steel alloy and an outer layer made of carbon steel or low-alloyed steel (see JP 61-123 496 A).
Furthermore, it is known to produce pressurized gas vessels from a round sheet metal workpiece by means of a flow forming machine (see DE 10 2006 039 656 B4). For this purpose, use is made of “monolithic” materials such as carbon steel, CrNi steel or (at low pressures) also aluminum.